# Chapter 7 - Nullability - Source Code is not null safe

**URL:** <https://forums.kodeco.com/t/chapter-7-nullability-source-code-is-not-null-safe/156332>\
**Category:** Dart Apprentice\
**Created:** [November 8, 2021, 11:46am UTC](https://forums.kodeco.com/t/chapter-7-nullability-source-code-is-not-null-safe/156332 "2021-11-08T11:46:57Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![dionv](https://assets.chunter.kodeco.com/user_avatar/forums.kodeco.com/dionv/32/105896_2.png) [@dionv](https://forums.kodeco.com/u/dionv)\
**Post date:** [November 8, 2021, 11:46am UTC](https://forums.kodeco.com/t/chapter-7-nullability-source-code-is-not-null-safe/156332/1 "2021-11-08T11:46:57Z")

</div>

Ironicially, the source code for Chapter 7 does not appear to use Dart 2.12.0 or higher, therefore it is not null safe by default, which could confuse folks.

So, if you hit this chapter, and are using the supplementayr materials, double-check your pubspec.yaml to make sure you have `sdk: '>=2.12.0 < 3.0.0'`

---

<div class="post-metadata">

**Author:** ![suragch](https://assets.chunter.kodeco.com/user_avatar/forums.kodeco.com/suragch/32/109020_2.png) [@suragch](https://forums.kodeco.com/u/suragch)\
**Post date:** [November 8, 2021, 12:23pm UTC](https://forums.kodeco.com/t/chapter-7-nullability-source-code-is-not-null-safe/156332/2 "2021-11-08T12:23:02Z")

</div>

Ironic, indeed! I can’t believe I missed that. I’ll put a high priority on updating the supplementary materials this week. It’s not just Chapter 7. It’s all the chapters. Thank you very much for leaving a comment about this!

---

<div class="post-metadata">

**Author:** ![suragch](https://assets.chunter.kodeco.com/user_avatar/forums.kodeco.com/suragch/32/109020_2.png) [@suragch](https://forums.kodeco.com/u/suragch)\
**Post date:** [November 9, 2021, 12:54am UTC](https://forums.kodeco.com/t/chapter-7-nullability-source-code-is-not-null-safe/156332/3 "2021-11-09T00:54:19Z")

</div>

Ah, I found the problem! The default branch on the GitHub repo is currently pointing to the `editions/1.0` branch. The null safety update uses the `editions/1.1` branch. The link to the 1.1 branch is here:

- [GitHub - raywenderlich/da-materials: The projects and the materials that accompany the Dart Apprentice book](https://github.com/raywenderlich/da-materials/tree/editions/1.1)

I also opened a GitHub issue to change the default branch to the current one.

- [https://github.com/raywenderlich/da-materials/issues/22](https://github.com/raywenderlich/da-materials/issues/22)

I’m glad that it turned out to be an easy fix and that I hadn’t forgotten something so basic as updating the Dart SDK environment version.

---

<div class="post-metadata">

**Author:** ![suragch](https://assets.chunter.kodeco.com/user_avatar/forums.kodeco.com/suragch/32/109020_2.png) [@suragch](https://forums.kodeco.com/u/suragch)\
**Post date:** [November 9, 2021, 4:32am UTC](https://forums.kodeco.com/t/chapter-7-nullability-source-code-is-not-null-safe/156332/4 "2021-11-09T04:32:06Z")

</div>

It has been fixed now. The default branch now points to the null safety version. Thank you again for bringing this up!

---

<div class="post-metadata">

**Author:** ![dionv](https://assets.chunter.kodeco.com/user_avatar/forums.kodeco.com/dionv/32/105896_2.png) [@dionv](https://forums.kodeco.com/u/dionv)\
**Post date:** [November 9, 2021, 11:32pm UTC](https://forums.kodeco.com/t/chapter-7-nullability-source-code-is-not-null-safe/156332/5 "2021-11-09T23:32:40Z")

</div>

Thanks for the quick responses and followup!